Rock drill positioning machine

ABSTRACT

A mount for a standard rock drill and feed unit is pivotally attached to the work end of a boom, which is swingably attached to preferably a rotary mount of unique type for positioning and holding such rock drilling unit at any selected location around a complete drilling circle whose size is determined by the extent of offset of the drill-carrying end of the boom from the axis of rotation of the rotary mount. The means swingably attaching the boom to the rotary mount is unique, in that it functions as a lever, utilizing a link or links and gearing attached to the held end of the boom to automatically advance or retract such boom longitudinally by proper amounts to maintain the drill-carrying end of the boom within a given transverse plane extending at right angles to the axis of rotation of the rotary mount, rather than within what would otherwise be an arcuate path of travel transversely of such axis. The machine also preferably includes a unique hydraulic pantograph arrangement for automatically maintaining the drilling unit mount at a given angle to the work throughout positioning movement of the boom. The special rotary mount utilizes power cylinders of standard leak-free type, together with gearing, to exert positive holding action on the boom at off-vertical positions. The special hydraulic pantograph utilizes slave piston and cylinder units to transmit hydraulic pressures generated by operation of the boom to hydraulic means for rotating the drilling unit mount about its pivot axis at the work end of the boom.

[ 51 Jan. 16,1973

[54] ROCK DRILL POSITIONING MACHINE Paul C. OLea'ry, Salt Lake City, Utah [73] Assignee: Bradley Pulverizer Company, Allentown, Pa. a part interest 22 Filed: Dec. 14, 1970 21 1 Appl. No.: 97,889

[75] Inventor:

Primary Examiner-J. Franklin Foss Attorney-Mallinckrodt & Cornaby [5 7 ABSTRACT A mount for a standard rock drill and feed unit is pivotally attached to the work end of a boom, which is swingably attached to preferably a rotary mount of unique type for positioning and holding such rock drilling unit at any selected location around a complete drilling circle whose size is determined by the extent of offset of the drill-carrying end of the boom from the axis of rotation of the rotary mount. The means swingably attaching the boom to the rotary mount is unique, in that it functions as a lever, utilizing a link or links and gearing attached to the held end of the boom to automatically advance or retract such boom longitudinally by proper amounts to maintain the drill-carrying end of the boom within a given transverse plane extending at right angles to the axis of rotation of the rotary mount, rather than within what would otherwise be an arcuate path of travel transversely of such axis. The machine also preferably includes a unique hydraulic pantograph arrangement for automatically maintaining the drilling unit mount at a given angle to the work throughout positioning movement of the boom. The special rotary mount utilizes power cylinders of standard leak-free type, together with gearing, to exert positive holding action on the boom at off-vertical positions. The special hydraulic pantograph utilizes slave piston and cylinder units to transmit hydraulic pressures generated by operation of the boom to hydraulic means for rotating the drilling unit mount about its pivot axis at the work end of the boom.

13 Claims, 1 1 Drawing Figures PATENTEDJMI 16 I975 SHEET 1 BF 5 INVEN TOR. PAUL C. OLEARY my AT TORNE YS PATENTEDJAH 16 ms SHEET 2 OF 5 INVENTOR. PAUL C. O'LEARY ATTORNEYS PATENTEU JAN 16 I975 INVENTOR. PAUL C. O' LEARY AT TORNE YS SHEET 3 [IF 5 IIAVI/ a W IIIIII W- =l IVAIlW ml:

PATENTEDJAH 16 I975 3.711.047

SHEET u 0F 5 INVENTOR. PAUL C. O'LEARY ATTORNEYS PATENTEDJAH 16 I975 SHEET 5 nr 5 HYDRAULIC FLUID RESERVOIR PUMP MOTOR LONGITUDINAL TRANSVERSE ROTAT INVEN'IIOR. PAUL c. OLEARY aW F AT TORNE YS ROCK DRILL POSITIONING MACHINE BACKGROUND OF THE INVENTION Field: The invention is in the field of machines for positioning rock drills for performing their intended work of drilling elongate holes in rock formations underground or on the surface of the earth in connection with mining and quarrying operations. Various aspects of the invention are applicable, however, to other machines, such as cranes, front end loaders, bucket lifts, etc., wherein a working part is positioned by a boom or the'like, e.g. the arms of a front end loader to which the bucket is attached.

State of the Art: Machines for mounting and positioning rock drills have long been known and extensively used for relieving manual labor and for obtaining greater accuracy in the placement and holding of rock drills for and during their operation. Efforts have been made to insure the drilling of rectilinear and strictly parallel holes in various series arrangements with a minimum of repositioning of the machine itself. To this end a variety of mechanisms have been combined heretofore in the construction of machines of the type concerned. Yet, there has remained the need for a truly versatile and accurate machine which is simple and convenient to operate and which is feasible to construct and maintain within the economic capability of many potential users of such equipment.

Many of the machines previously developed have been of boom type, employing a swingable boom or jib extending from and pivotally mounted on a vehicle or other support, as adjustable mounting means for the rock drill and its feed mechanism. Such boom or jib is pivotally attached to the vehicle for movement from side-to-side and up and down, so considerable versatility is achieved with respect to placement of the individual bore holes relative to one another. In at least one instance (Thompson U. S. Pat. No. 3,226,064), provision has been made for so-called roll-over" of the drill and its feed mechanism by mounting them directly on a receiving member rotatably carried by and projecting from the drill-carrying end of the pivoted boom or jib, so the drill can be adjustably positioned along a circular path about the axis of rotation of thecarried boom member.

SUMMARY OF THE INVENTION In accordance with a preferred form of the present invention, the boom is itself mounted for roll-over movement about an axis of rotation. Such boom is swingably attached to a rotary mount, which provides rotary movement through a full 360 in opposite directions as a rock shaft relative to supporting means in the form of a vehicle or a stationary support. Thus, the entire swingable boom executes roll-over movement. This is a highly significant feature, for it provides far greater versatility than has been obtainable heretofore in the size of the circular path along which the drill can be adjustably positioned.

The boom-rotating means may be of any suitable type, but is preferably a unique mechanism comprising standard, leak-free, fluid-actuated, power cylinders arranged to reciprocate a roller chain about a bull wheel sector and over a sprocket wheel, the latter being affixed to a shaft carrying the rotary mount for the boom.

Whether or not the boom is mounted for rotation, as normally it isnt in the instance of a crane, a front end loader, or a bucket lift, it is swingably attached to its supporting means in accordance with this invention by unique mechanism insuring automatic extension or retraction along its longitudinal axis by amounts required to maintain its work, i.e. carrying, end within a given plane extending transversely of the boom. This means that such work or carrying end of the boom does not back away from or override an initial work position as the boom is being raised or lowered or moved from side-to-side, but is kept precisely in line with such initial work position. Although this result has been achieved in other ways prior to this invention, the present mechanism is uniquely advantageous, especially in its combinational tie-in with the other mechanisms and structure of overall machine here disclosed. Thus, at least one link is pivotally secured at one of its ends to the rotary mount for the boom and has the mounting end of the boom pivotally secured to its other end. Gearing secures such mounting end of the boom to the rotary mount on the basis of a given ratio determined by the particular transverse plane in which it is desired that the work end of the boom or of the particular item carried thereby be maintained. In the case of the rock drilling machine of the invention as here specifically disclosed, such plane extends at right angles to the axis of rotation of the rotary mount.

It is advantageous that the mount for the rock drilling unit at the carrying end of the boom be automatically rotated about its pivotal axis as the boom is being operated to maintain the several drilling positions of the drill in parallel, so the series of holes drilled will be in parallel. To this end, a unique hydraulic pantograph is provided comprising slave piston and cylinder units controlling the hydraulic flow of fluid to hydraulic means that moves such drilling unit mount around its pivot axis. The slave units derive their motion from rotational movement of the link or links of the boom attaching means about the pivot axis thereof, advantageously by roller chain and sprocket gearing connection to the pistons of such slave units.

THE DRAWINGS A specific embodiment representing the best mode presently contemplated of carrying out the invention is illustrated in the accompanying drawings in which:

FIG. 1 is a view in side elevation of a rock drill positioning machine of the invention mounting a standard rock drill and feed unit and with its boom completely retracted to the horizontal for positioning the drill at selected locations around a circle of minimum diameter, several extended positions of the boom being shown by dotted lines to indicate how the drill bit can be maintained parallel from position to position with its tip in the same transverse plane;

FIG. 2, a fragmentary top plan view taken from the standpoint of the line 22 of FIG. 1 and drawn to a considerably larger scale, part of the housing for the boom-rotating means being broken away to reveal interior, working parts;

FIG. 3, a transverse vertical section taken along the line 3-3 of FIG. 2;

FIG. 4, a similar transverse vertical section taken along the line 4-4 of FIG. 2;

FIG. 5, a fragmentary longitudinal vertical section taken along the line 55-of FIG. 2;

FIG. '6, another fragmentary longitudinal vertical section taken along the line 6-6 of FIG. 2, with an extended position of the boom being shown by dotted lines;

FIG. 7, a fragmentary horizontal section taken on the line 7-7 of FIG. 6, drawn in elevation on one side of the longitudinal center line with duplicate details concealed;

FIG. 8, still another fragmentary longitudinal vertical section taken along the line 88 of FIG. 2 to show certain of the working parts of the means swingably attaching the boom to the rotary mount;

FIGS. 9 and 10, views corresponding to that of FIG. 8 but illustrating the working parts in different extended positions of the boom; and

FIG. 1l,'a flow diagram of the hydraulic system for operating and controlling the machine.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENT In the presently preferred form illustrated, the machine of the invention comprises a boom 10 swingably attached at one of its ends to a rotary mount 11, which, in turn, is rotatably carried by boom-rotating means indicated generally at 12. The opposite or working-end of boom 10 pivotally carries slideway mounting means 13 for a standard rock drill and drill feed unit indicated generally at 14.

The means swingably attaching boom 10 to rotary mount 11 is of unique construction and advances. or retracts the boom longitudinally as such boom is raised or lowered, so as to automatically keep the cutting tip of the drill bit 14a in a transverse plane P, FIG. 1, that extends at right angles to the axis of rotation of the rotary mount 11. Such attaching means is indicated generally at 15, FIG. 5. Additionally, hydraulic pant'ograph mechanism, indicated generally at 16, FIGS. 5 and 6, serves to maintain the drill parallel from one drilling position to another. I

BOOM-ROTATING MEANS at off-vertical positions thereof that could otherwise present troublesome torque problems.

The illustrated boom-rotating means 12 is adapted to be mounted on a vehicle or other suitable support, as by means of bolts (not shown) passed through bolt holes 17, FIG. 5, and supports the remainder of the machine. As shown in FIGS. 2, 3, 4, and 5, such boomrotating means utilizes a pair of standard, leak-free, hydraulic power cylinders 18 mounted in a housing 19 to rock a shaft 20 by means ofa cross head 21 keyed to the shaft, see particularly FIGS. 3 and 5. Shaft 20 extends entirely through housing 19, being journaled at its opposite ends by bearings 22, FIG. 5. Power cylinders 18 are pivotally held at 18a between walls 19a interiorly of the housing and are supplied with hydraulic fluid from a reservoir 23, FIG. 11, through appropriate flow lines, as indicated, and under pressure supplied by a pump 24 under control of the operator by means of his activating the particular one of directional control valves 25 which is designated rotation. Reciprocation in mutually opposite directions of the pistons 18b of such power cylinders imparts rocking movement to 5 shaft 20.

Also keyed to rock shaft 20 is a multi-channeled bull wheel sector 26, FIGS. 4 and 5, which is connected by roller chains 27 to a correspondingly multi-sprocketed wheel 28 keyed to a power output shaft 29. Chains 27 are kept tight by a take-up device 30, FIG. 4, and the several parts are so proportioned that the reciprocative stroke of the piston 18b of a power cylinder 18 will effect full 360 rotation of sprocket wheel 28 in one or the other direction. Power output shaft 29 extends through bearings 31, FIG. 5, and projects therefrom to receive sleeve 11a of rotary mount 11 in securely keyed relationship. It should be noted that partial activation of a power cylinder 18 will effect a positive holding action on rotary mount 11 by reason of the hydraulic pressure, regardless of torque imposed thereon by any off-vertical position of the boom-carried rock drill and drill feed unit.

It should be realized that the bull wheel, roller chain, and sprocket arrangement specifically shown is a most advantageous gearing arrangement for transmitting motion of shaft 20 to shaft 29, because of its strength and effective operation over extended periods of time and provision for taking up slack due to wear. It is the best mode presently contemplated of carrying out this phase of the invention. However, other forms of gearing could be employed, e.g. the sprocket wheel 28 could be a gear, with the bull wheel sector an intermeshing gear or gear sector.

BOOM-OPERATING MEANS The means swingably attaching the boom to the rotary mount, so it can be raised or lowered and moved laterally from side to side, constitutes a lever fulcrumed by pivotal securement to rotary mount 11 for advancing or retracting the boom longitudinally, as it is being raised or lowered, so as to maintain the tip of the drill bit in the same transverse plane regardless of how the boom is swung.

In the form illustrated and designated 15, such attaching means comprises a pair of links 32, FIG. 2, pivotally secured at one set of ends to respective bifurcations, i.e. arms Ilb, of rotary mount 11 by means ofa pivot shaft 33 to which they are keyed. Such shaft 33 is journaled in bearing portions 110 of rotary mount 11 as a rock shaft, so boom 10 may be raised and lowered or otherwise moved transversely of its length. Fixedly secured to bearing portions 110 are respective sprocket wheels, see the wheel 34, FIG. 7, which are connected to other sprocket wheels, respectively, see 35, by respective roller chains, see 36. Sprocket wheels 35 are fixedly secured to respective stub shafts 37, which are, in turn, fixedly secured to the respective bifurcations 10a of boom 10, as well as being journaled in the opposite set of ends of links 32 by respective bearings, see 38.

Roller chains 36 are anchored, as at 36a, FIGS. 8, 9, and 10, to the respective fixed sprocket wheels 34, so that, in operation of the machine, as the boom 10 is raised and lowered and the sprocket wheels fixed thereto are rotated about their respective axes as pivotal centers of the held end of the boom, such sprocket wheels and the corresponding held end of the boom travel along the roller chains 36 and carry along with them the corresponding ends of respective links 32. Because the opposite ends of links 32 are pivotably mounted in arms 11b, such links 32 constrain the held end of boom to move around the pivotal axes of the links, i.e. around the axis of shaft 33, in a circular orbit, but such held end is still free to move relative to the links. By appropriate engineering design in any given instance with respect to dimensioning of the component parts relative to one another, boom 10 can be made to move forwardly or backwardly, automatically, as it is being raised or lowered about the axis of shaft 33 from a vertical position, by the precise distances necessary to keep the cutting tip of drill bit 14a within a given transverse plane. In the present instance, as previously indicated, the parts are so designed as to maintain the cutting tip of drill bit 14a in a plane P, FIG. 1, that extends at right angles to the axis of rotation of rotary mount 11.

For powering boom 10, i.e. moving it transversely relative to its longitudinal axis, one end of a main power cylinder 39 is pivotally attached to and between the tip ends of the bifurcations of arm llb by means of a pin 40. The piston rod 390 of such power cylinder is pivotally attached by a pivot pin 41 to and between a pair of lugs 42, FIG. 6, rigidly secured to a structural cross member 43, which is, in turn, rigidly secured to and between the bifurcations 10a of boom 10. Main power cylinder 39 derives its power from hydraulic fluid pumped by pump 24, FIG. 11, and passed through suitable flow lines under the control of the particular valve designated transverse.

It should be realized that forms of gearing other than sprocket wheels and roller chains can be used in the lever means described above, e.g. the sprocket wheels may be gears and the roller chain another gear.

HYDRAULIC PANTAGRAPl-I The mounting means 13 for drill and drill feed unit 14 is pivotally mounted on the work end of boom 10 by means of a pin 44 and is maintained parallel from one drilling position to another by the hydraulic pantagraph arrangement 16, which, in the form here shown, includes slave piston and cylinder units 45, FIGS. 5 and 11; power cylinder 46 pivotally attached to and between the tip ends of lugs 42 by a pivot pin 47 and having oppositely extending piston rods 46a, respectively, of equal diameters extending through respective ends of the cylinder; a pair of lugs 48 to which one of the piston rods 46a is pivotally attached by means of a pin 49; hydraulic circuit 50 and 51 respectively interconnecting sets of opposite ends of units 45, the power cylinder 46 being interposed in circuit 51; and a roller chain and sprocket connection (detailed herebelow) between slave units 45 and rock shaft 33 for powering such slave units from the rock shaft.

The cylinders of slave units 45 are secured in web 11d of rotary mount 11 between the arms 11b thereof. Fixed to rock shaft 33 between bearing hubs 110 is a sprocket wheel 52, FIGS. 5 and 7, engaged by a length of roller chain 53 whose ends are secured, respectively, to piston rods 45a of slave units 45.

HYDRAULIC SYSTEM The hydraulic system for the machine, FIG. 11, includes supply and return lines 54 and 55, respectively, with check valve 56 interposed in supply line 54 and with pressure relief valves 57 interposed in return line 55.

As previously described, the hydraulic system contains a reservoir 23 for hydraulic fluid and a pump 24 for pressurizing the liquid, which is usually oil. The pressurized liquid is directed to particular flow circuits by means of control valves 25, which may be of standard design equipped with operating handles 25a.

Also as previously described, the valve designated rotation controls flow of hydraulic fluid to and from power cylinders 18, and the valve designated transverse controls flow to and from power cylinder 39. The valve designated slave controls flow to and from slave unit and power cylinder circuits 50 and 51, while the valve designated longitudinal controls flow to and from a power cylinder 58, FIG. 6, which is secured to rock drill and feed unit mounting means 13 at 59 and whose piston rod 58a is secured to drilling unit 14 at 60.

OPERATION In operation, one or more of the valves 25 are individually manipulated by the operator to place drilling unit 14 in the position desired for drilling the first of a series of holes to be drilled in a rock face, e.g. a face corresponding to the plane P.

Following the drilling of such a hole, additional holes can be quickly and easily drilled in accordance with any given drilling pattern. Thus, the respective valves 25 controlling rotation of boom 10 about the axis of rotation provided by power output shaft 29 of boom rotating means 12 and controlling transverse movement of boom 10 with respect to such axis may be manipulated to place drill bit 14a exactly in line with said axis or to effect rotation and roll over of drilling unit 14 about a full circle concentric with shaft 29 and of desired radius, with periodic drilling stops as and when required. By reason of the unique boom-attaching means 15 here disclosed as part of the boomoperating means, the cutting tip of drill bit 14a will automatically remain in the plane P.

If at any time for some reason, it is necessary or desirable to move the cutting tip of drill bit 14a forwardly or backwardly relative to the given plane, e.g. due to an uneven rock face, the valve 25controlling longitudinal movement of drilling unit 14 through power cylinder 53 is manipulated. Meanwhile, drilling unit mounting means 13 will be automatically maintained at right angles to the transverse plane by means of hydraulic pantagraph 16. The control valve 25 designated slave is provided so the hydraulic balance of slave units 45 can be altered as may be required from time to time during operation of the machine to place drilling unit mounting means 13 and its carried drilling unit 14 at some other angle to the transverse plane than the right angles previously mentioned. This makes the machine completely versatile.

It has been found that unless the volumetric capacities of slave units 45 are precisely equal, which, from a practical standpoint is next to impossible (a difference of a four thousandth of an inch in cylinder bore diame ter cannot be tolerated), pressure relief must be provided for the hydraulic fluid in the flow lines serving the circuits50 and 51; otherwise roller chain 53 will be torn apart. Pressure relief valves 57 are provided for this purpose.

Whereas this invention is here illustrated and described with respect to a certain preferred form thereof, it is to be understood that many variations are possible without departing from the inventive concepts particularly pointed out in the claims.

lclaim:

1. A machine for positioning and holding a rock drilling unit or other item, comprising a boom or the like having a work end adapted to receive the rock drilling unit or other item and a held end; means for supporting the boom; lever means swingably attaching the held end of the boom to the supporting means, said lever means being adapted to advance or retract the boom longitudinally as it is being swung transversely and comprising link means pivotally secured adjacent one end thereof to thehsupporting means and pivotally secured adjacent the opposite end thereof to the held end of the boom, and gearing anchored at the pivotal securement of the said one end of the link means as a fulcrum and movably interconnecting said held end of the boom therewith, whereby swinging of the boom will cause the held end of the boom to move in a circular orbitaround said axis of pivotal securement of the link means to the supporting means at a predetermined ratio relative to the transverse movement of the boom; and means for swinging the boom transversely of its length.

2. A machine in accordance with claim 1, wherein the meansfor supporting the boom is a rotary mount having its axis of rotation extending longitudinally of the boom; and there are included means for rotating said mount transversely through full circles from sideto-side, respectively, of the boom.

3. A machine in accordance with claim 2, wherein the means for rotating the mount comprise a pair of hydraulic power cylinders; a rotatably mounted crosshead to opposite ends of which the respective power cylinders are connected; a rotary output shaft to which the mount is fixedly secured; and gearing rotatably connecting said crosshead to said rotary output shaft.

4. A machine in accordance with claim 3, wherein the gearing comprises a bull wheel sector rotatably mounted for rocking movement from side-to-side; a sprocket wheel fixedly secured to the output shaft; a length of roller chain looped about said sprocket wheel and extended over said bull wheel sector with its ends secured at opposite sides thereof; the crosshead being connected to said bull wheel sector for rocking movement therewith; wherein the means for swinging the boom is a'hydraulic power cylinder; and wherein there is provided a hydraulic system for operating the hydraulic power cylinders.

5. A machine in accordance with claim 4, wherein elongate mounting means for the rock drilling unit or other, item is pivotally secured to the carrying end of the boom; and means, including hydraulic power cylinders connected into the hydraulic system, are provided for maintaining said mounting means in parallelism as the boom is operated.

6. A machine in accordance with claim 5, wherein the means for maintaining the mounting means in parallelism comprise a hydraulic power cylinder for moving said mounting means about its pivot axis; a pair of hydraulic power cylinders in the form of piston and cylinder units connected into the hydraulic system in mutual opposition for causing hydraulic fluid to flow to and from the first-named power cylinder; and means for driving said piston and cylinder units in mutual opposition from the pivotal movement of the one endof the link means.

7. A machine in accordance with claim 6, wherein the rotary mount for the boom comprises a rotary shaft having a bifurcated arm extending transversely of its axis; the one end of the link means is mounted for pivotal movement by being fixedly secured to a shaft journaled in and between the bifurcations of said arm; and the means for driving the piston and cylinder units comprise a sprocket wheel fixedly secured to the lastnamed shaft, and a length of roller chain looped around said sprocket wheel and having its ends attached to the movable elements of the piston and cylinder units, respectively.

8. A machine in accordance with claim 6, wherein the hydraulic power cylinder for moving the mounting means for the rock drilling unit or other item has a movable piston with oppositely extending piston rods of the same diameter extending through opposite ends of the cylinder, respectively, so the quantity of hydraulic fluid displaced from one end of the cylinder will equal the quantity of hydraulic fluid introduced into the opposite end of the cylinder.

9. A machine in accordance with claim 8, wherein pressure relief valves are provided in that portion of the hydraulic system associated with the means for maintaining the mounting means in parallelism, so quantities of hydraulic fluid directed to and from the power cylinders thereof will be balanced automatically.

10. A machine in accordance with claim 1, wherein the gearing for the lever means comprises a gear wheel fixed to the supporting means and concentric with the axis of the pivotal securement of the link means to said supporting means; a gear wheel fixed to the held end of the boom and concentric with the axis of the pivotal securement of the link means to such held end of the boom; and gear means interconnecting said gear wheels.

11. A machine in accordance with claim 9, wherein the gear wheels are sprocket wheels and the gear means interconnecting the gear wheels are respective roller chains.

12. A machine in accordance with claim 1, wherein the held end of the boom is bifurcated; themeans for supporting the boom comprises mutually spaced supports encompassed by the bifurcations of said held end of the boom; the lever means includes a shaft extending between and journaled in said supports; the link means comprises a pair of links fixedly secured at one set of corresponding ends thereof to said shaft in mutually spaced relationship; the gearing comprises a pair of sprocket wheels fixedly secured, respectively, to said supports concentrically with said shaft, a second pair of sprocket wheels fixedly secured, respectively, to said bifurcations of the boom in alignment with the first pair of sprocket wheels, and a pair of roller chains interconnecting respective sets of corresponding sprocket 13. A machine in accordance with claim 11, wherein the means for swinging the boom transversely of its length is a hydraulic power cylinder interposed between and connected to the boom and the supports. 

1. A machine for positioning and holding a rock drilling unit or other item, comprising a boom or the like having a work end adapted to receive the rock drilling unit or other item and a held end; means for supporting the boom; lever means swingably attaching the held end of the boom to the supporting means, said lever means being adapted to advance or retract the boom longitudinally as it is being swung transversely and comprising link means pivotally secured adjacent one end thereof to the supporting means and pivotally secured adjacent the opposite end thereof to the held end of the boom, and gearing anchored at the pivotal securement of the said one end of the link means as a fulcrum and movably interconnecting said held end of the boom therewith, whereby swinging of the boom will cause the held end of the boom to move in a circular orbit around said axis of pivotal securement of the link means to the supporting means at a predetermined ratio relative to the transverse movement of the boom; and means for swinging the boom transversely of its length.
 2. A machine in accordance with claim 1, wherein the means for supporting the boom is a rotary mount having its axis of rotation extending longitudinally of the boom; and there are included means for rotating said mount transversely through full circles from side-to-side, respectively, of the boom.
 3. A machine in accordance with claim 2, wherein the means for rotating the mount comprise a pair of hydraulic power cylinders; a rotatably mounted crosshead to opposite ends of which the respective power cylinders are connected; a rotary output shaft to which the mount is fixedly secured; and gearing rotatably connecting said crosshead to said rotary output shaft.
 4. A machine in accordance with claim 3, wherein the gearing comprises a bull wheel sector rotatably mounted for rocking movement from side-to-side; a sprocket wheel fixedly secured to the output shaft; a length of roller chain looped about said sprocket wheel and extended over said bull wheel sector with its ends secured at opposite sides thereof; the crosshead being connected to said bull wheel sector for rocking movement therewith; wherein the means for swinging the boom is a hydraulic power cylinder; and wherein there is provided a hydraulic system for operating the hydraulic power cylinders.
 5. A machine in accordance with claim 4, wherein elongate mounting means for the rock drilling unit or other item is pivotally secured to the carrying end of the boom; and means, including hydraulic power cylinders connected into the hydraulic system, are provided for maintaining said mounting means in parallelism as the boom is operated.
 6. A machine in accordance with claim 5, wherein the means for maintaining the mounting means in parallelism comprise a hydraulic power cylinder for moving said mounting means about its pivot axis; a pair of hydraulic power cylinders in the form of piston and cylinder units connected into the hydraulic system in mutual opposition for causing hydraulic fluid to flow to and from the first-named power cylinder; and means for driving said piston and cylinder units in mutual opposition from the pivotal movement of the one end of the link means.
 7. A machine in accordance with claim 6, wherein the rotary mount for the boom comprises a rotary shaft having a bifurcated arm extending transversely of its axis; the one end of the link means is mounted for pivotal movement by being fixedly secured to a shaft journaled in and between the bifurcations of said arm; and the means for driving the piston and cylinder units comprise a sprocket wheel fixedly secured to the last-named shaft, and a length of roller chain looped around said sprocket wheel and having its ends attached to the movable elements of the piston and cylinder units, respectively.
 8. A machine in accordance with claim 6, wherein the hydraulic power cylinder for moving the mounting means for the rock drilling unit or other item has a movable piston with oppositely extending piston rods of the same diameter extending through opposite ends of the cylinder, respectively, so the quantity of hydraulic fluid displaced from one end of the cylinder will equal the quantity of hydraulic fluid introduced into the opposite end of the cylinder.
 9. A machine in accordance with claim 8, wherein pressure relief valves are provided in that portion of the hydraulic system associated with the means for maintaining the mounting means in parallelism, so quantities of hydraulic fluid directed to and from the power cylinders thereof will be balanced automatically.
 10. A machine in accordance with claim 1, wherein the gearing for the lever means comprises a gear wheel fixed to the supporting means and concentric with the axis of the pivotal securement of the link means to said supporting means; a gear wheel fixed to the held end of the boom and concentric with the axis of the pivotal securement of the link means to such held end of the boom; and gear means interconnecting said gear wheels.
 11. A machine in accordance with claim 9, wherein the gear wheels are sprocket wheels and the gear means interconnecting the gear wheels are respective roller chains.
 12. A machine in accordance with claim 1, wherein the held end of the boom is bifurcated; the means for supporting the boom comprises mutually spaced supports encompassed by the bifurcations of said held end of the boom; the lever means includes a shaft extending between and journaled in said supports; the link means comprises a pair of links fixedly secured at one set of corresponding ends thereof to said shaft in mutually spaced relationship; the gearing comprises a pair of sprocket wheels fixedly secured, respectively, to said sUpports concentrically with said shaft, a second pair of sprocket wheels fixedly secured, respectively, to said bifurcations of the boom in alignment with the first pair of sprocket wheels, and a pair of roller chains interconnecting respective sets of corresponding sprocket wheels, said chains being fixedly secured on the respective sprocket wheels of the said first pair; and the said bifurcations of the held end of the boom being journaled, respectively, in the opposite set of corresponding ends of the links concentrically with the said second pair of sprocket wheels.
 13. A machine in accordance with claim 11, wherein the means for swinging the boom transversely of its length is a hydraulic power cylinder interposed between and connected to the boom and the supports. 